README.rst

Team and repository tags

Swift

A distributed object storage system designed to scale from a single
machine to thousands of servers. Swift is optimized for multi-tenancy
and high concurrency. Swift is ideal for backups, web and mobile
content, and any other unstructured data that can grow without bound.

Swift was originally developed as the basis for Rackspace's Cloud Files
and was open-sourced in 2010 as part of the OpenStack project. It has
since grown to include contributions from many companies and has spawned
a thriving ecosystem of 3rd party tools. Swift's contributors are listed
in the AUTHORS file.

Docs

To build documentation install sphinx (pip install sphinx), run
python setup.py build_sphinx, and then browse to
/doc/build/html/index.html. These docs are auto-generated after every
commit and available online at
http://docs.openstack.org/developer/swift/.

For Developers

Getting Started

Swift is part of OpenStack and follows the code contribution, review, and testing processes common to all OpenStack projects.

If you would like to start contributing, check out these
notes to help you get started.

The best place to get started is the
"SAIO - Swift All In One".
This document will walk you through setting up a development cluster of
Swift in a VM. The SAIO environment is ideal for running small-scale
tests against swift and trying out new features and bug fixes.

Tests

There are three types of tests included in Swift's source tree.

Unit tests

Functional tests

Probe tests

Unit tests check that small sections of the code behave properly. For example,
a unit test may test a single function to ensure that various input gives the
expected output. This validates that the code is correct and regressions are
not introduced.

Functional tests check that the client API is working as expected. These can
be run against any endpoint claiming to support the Swift API (although some
tests require multiple accounts with different privilege levels). These are
"black box" tests that ensure that client apps written against Swift will
continue to work.

Probe tests are "white box" tests that validate the internal workings of a
Swift cluster. They are written to work against the
"SAIO - Swift All In One"
dev environment. For example, a probe test may create an object, delete one
replica, and ensure that the background consistency processes find and correct
the error.

You can run unit tests with .unittests, functional tests with
.functests, and probe tests with .probetests. There is an
additional .alltests script that wraps the other three.

Code Organization

bin/: Executable scripts that are the processes run by the deployer

doc/: Documentation

etc/: Sample config files

examples/: Config snippets used in the docs

swift/: Core code

account/: account server

cli/: code that backs some of the CLI tools in bin/

common/: code shared by different modules

middleware/: "standard", officially-supported middleware

ring/: code implementing Swift's ring

container/: container server

locale/: internationalization (translation) data

obj/: object server

proxy/: proxy server

test/: Unit, functional, and probe tests

Data Flow

Swift is a WSGI application and uses eventlet's WSGI server. After the
processes are running, the entry point for new requests is the
Application class in swift/proxy/server.py. From there, a
controller is chosen, and the request is processed. The proxy may choose
to forward the request to a back- end server. For example, the entry
point for requests to the object server is the ObjectController
class in swift/obj/server.py.

For Deployers

There is an ops runbook
that gives information about how to diagnose and troubleshoot common issues
when running a Swift cluster.

You can run functional tests against a swift cluster with
.functests. These functional tests require /etc/swift/test.conf
to run. A sample config file can be found in this source tree in
test/sample.conf.